My pal Steve Cirone and and I got together and spent a few minutes comparing cameras.

These are crops made from each camera. Each is shown at the same magnification. Each complete image, printed at the same magnification as these crops, would print 56" (140cm) wide!

Have a look:

This shows what I expected: the 1Ds is sharper at huge magnifications than the 5D, which is again sharper than the D3.

We also could have spent hours trying to get the images to look more like each other, but this shows what's important. I can't show here, but have played with numerous other lenses and camera settings, and these results are showing what the cameras do. Better lenses or different sharpening settings didn't change anything, so don't start trying to Monday-morning quarterback "but if Rockwell just changed ... then the ... would look better." There wasn't any wind and these results were repeatable and solid. Truth is told.

Technik

I made several shots with each to ensure no camera had a dud.

The Canons used a new 70-200mm f/4 IS, the sharpest zoom I've ever used, set to 100mm.

The D3 used an 80-200mm f/2.8 AF, also a super-sharp lens with more resolution than any of these cameras, set to 100mm.

Exposures were about f/5.6 at 1/200 at about ISO 200.

All images were resized (Photoshop bi-cubic) to match the largest image, 5,616 pixels wide.

They were cropped to the size shown above, and presented here.

I use natural images instead of buildings because nature is fractal, meaning it has detail at every amplitude, at every frequency (fineness of detail), and in every direction. Charts and buildings with sharp edges only have details at some frequencies, some amplitudes and in only in some directions. An educated eye can see more with a natural image.

Summary

These are crops from huge prints. Seen from a normal distance, they'll look the same as far as fine detail goes.

Since the Nikon uses more gross sharpening at lower spatial frequencies and has slightly higher contrast as set here, standing 10 feet (3m) away the Nikon would look the sharpest. Try it yourself, presuming you're a photographer with a 30" screen to show all three at once and not just an online expert on a laptop.

If you stick your nose in them as we do here, yes, either Canon has finer detail than the Nikon, and the 1Ds has finer detail then the 5D.

It makes sense that the Nikon has less fine detail: the D3 is a sports, news and action camera optimized for speed, while each of these Canons is much slower and optimized for fine image quality. When the Nikon D3x hits, we'll have a different story. As I keep saying, if landscapes are your thing, the D3 is not the camera to use, it's a 4x5."

We're seeing the limits of each camera's sensor, not these lenses. Sharper lenses wouldn't change anything here; all the lenses used have far more resolution than any of these cameras can resolve. A softer lens used on the 1Ds Mk III would look very different than the limited resolution and too-large a diameter sharpening kernel as used by the D3.